This invention relates to a new and improved apparatus and method for controlling the tension in continuous filaments or webs of flexible materials such as yarn, paper, cardboard, plastic films, metal foils, wire, and other materials. Users of knitting machines, rotary printing presses, wire-winding devices, and other types of standard equipment are constantly experiencing problems directly related to the tension in the materials that are fed to these machines.
In the past, various tension control devices have been employed utilizing different concepts with varying degrees of success. The earliest tension control devices employed weights suspended from the continuous material to add a constant tension or "drag" on the continuously traveling material. In other applications, springs, gates, clamps as well as electronic, mechanical and electromechanical devices have been employed which apply a frictional force to the material being supplied at the machine takeup. All of the prior devices heretofore known have had various problems including the uneven application of "drag" forces applied to the material. The problem of maintaining a constant and uniform tension on a continuous moving flexible material has been difficult to resolve and has been compounded by the uneven or erratic takeup or consumption of the apparatus to which the material is supplied.
Most tension control devices heretofore devised have operated by applying a frictional force to the continuous material as it is being directed along its feed path. These frictional forces are difficult to regulate and are uneven as the machine which consumes the material operates often in an intermittent as well as in an irregular fashion which compounds the problems of uniform feed at a constant tension.
It is one object of this invention to provide a tension control device which will control delivery of a continuously or intermittently moving material under a uniform and constant tension to the machine takeup where the material is to be consumed or used.
Another object of this invention is to provide a tension control device which will provide equally uniform tensions irrespective of the rate of material travel along a directed path.
Yet another objective of this invention is to provide a tension control device wherein the tension may be easily regulated to a precise degree, irrespective of the surface properties of the material being supplied and is relatively inexpensive to construct.
Still another objective of this invention is to provide a method for controlling the tension uniformly on a continuous material whether traveling continuously or intermittently to a takeup device.
Other objectives of this invention will become readily apparent to one skilled in the art from the following detailed description of the drawings and a preferred embodiment, and the included description and claims are not intended to limit the scope of the invention.